The present invention relates in general to electrical comparators and in particular to a central annunciator system for monitoring the status of various avionics systems and other aircraft sensors using such comparators.
Many aircraft systems and sensors require frequent monitoring or scanning by the pilot in order to detect potential problems. Large aircraft such as jet transports have built-in annunciator panels which provide automated scanning. Smaller aircraft, however, do not provide for automated scanning causing the pilot to often sacrifice his continuous physical scanning in order to conduct other necessary tasks.
Annunciator systems that are commonly found in the aircraft field provide for devices such as comparators that are used for monitoring input such as voltages.
U.S. Pat. No. 4,996,520 provides for an over-voltage detection test apparatus for military aircraft weapon systems using an electrical connector for interfacing the test apparatus with an aircraft power supply and an electrical comparator that can pass the voltages from first and second inputs. The first input is clamped to a voltage which is representative of the maximum voltage limit of the missiles of the aircraft. The second input is tied to the output of the aircraft power supply so as to vary with the power supply output. An alarm circuit is activated by the comparator when the second input voltage exceeds the first input voltage thus warning the operator of over-voltage conditions. The test apparatus is very complex and directed specifically to the F-16 fighter aircraft and its missile functions.
U.S. Pat. No. 3,641,546 for a high-low voltage level sensor uses a pair of comparators for monitoring voltage levels. Two comparators are used to monitor a single input, particularly, the voltage. High and low level voltages monitored by the comparator produce a signal that is used to energize an alarm device. The sensor cannot be customized and the alarm device must be terminated by disconnecting the input or turning off the unit entirely.
U.S. Pat. No. 3,789,242 is for an over-voltage and undervoltage detection circuit having a voltage comparator. The voltage comparator uses multiple reference voltage sources and is not suitable for multiple-input monitoring.
The annunciator systems found in the prior art employ separate alarm circuits for each function monitored. Thus, in a multiple-function arrangement, multiple alarm circuits would add a great deal of circuitry to the system and prove to be very costly.
It is known in the prior art to customize the inputs in a comparator through the use of internal switches or jumpers. These parts commonly used for customization are costly, require precious space and require either a hole or opening in the comparator box in order to allow sufficient access for customization. Moreover, it is not desirable to open a box in order to customize the comparator devices.
At present, there is no known central annunciator device that can be adapted to a wide variety of existing aircraft. Additionally, there is no known annunciator device that provides for a customizable unit, a distraction-free unit, a low-cost unit, an easy-installable unit, an interference-free unit, a fail-safe unit, a self-powered unit, and a multiple alert handling capability unit.